1. Field of the Invention
The present invention is related to a driving force distribution control apparatus for performing both a driving force distribution between a front wheel and a rear wheel and a driving force distribution between a left wheel and a right wheel.
2. Related Art
Recently, a large number of technical ideas as to vehicles have been proposed which actively control not only driving force distributions between front wheels and rear wheels, but also driving force distributions between right wheels and left wheels in order to improve stabilities and turning round characteristics of these vehicles.
For instance, disclosed in JP-A-07-108840 is a technical idea capable of controlling a torque distribution between a front wheel and a rear wheel by a differential limiting clutch provided on a center differential, and also capable of controlling a torque distribution between a left wheel and a right wheel by a torque transfer mechanism. The torque transfer mechanism is constituted by a gear shifter mechanism and a transfer capacity variable control type torque transfer mechanism, which are provided on a rear differential.
However, the technical idea disclosed in JP-A-07-108840 owns the following problem. That is, since the driving force distribution control for the front and rear wheels and the driving force distribution control for the right and left wheels are independently carried out in response to the driving conditions of the vehicle, in such a case that both the control operation by which the driving force of the front and rear wheels is distributed so as to apply yaw moment to the vehicle, and the control operation by which the driving force of the right and left wheels is distributed so as to apply yaw moment to the vehicle are actuated, these control operations may be overlapped with each other, or may interfere with each other, depending upon the operation timing thereof. Then, the vehicle is brought into unstable driving condition, or the target effect may not be achieved in accordance with values of yaw moment which are applied to the vehicle.